Bees collect a gummy plant resin called propolis on their back legs and use it to line the entries to the hive, making those hives some of the most sterile environments on Earth. Researchers at the U are finding that propolis may also help fight AIDS.

Propolis: an ancient remedy may fight AIDS

an ancient remedy may fight AIDS

By Deane Morrison

Published on May 24, 2004

As if bees don't do enough for us already, U of M researchers
have recruited the busy insects in the fight against AIDS. Bees
collect a plant resin that inhibits growth of the AIDS virus in
laboratory cultures, and the researchers are exploring its
potential as a source of a new anti-HIV drug. Called propolis, the
gummy substance has been used medicinally since ancient times. It
helps control bacteria, inflammation, infectious yeast, and
viruses, and you can buy it commercially in a variety of
formulations. "It's actually resin from particular trees--birch,
poplar, some conifers," says bee expert Marla Spivak, an associate
professor of entomology at the U. "Bees pick it up on their back
legs and use it to line the entries to the hive and to seal cracks
in the hive." Thanks largely to propolis, beehives are one of the
most sterile environments on Earth--a good thing for a dwelling
with thousands of inhabitants. According to Phil Peterson,
professor of medicine and director of the University's Division of
Infectious Diseases and International Medicine, the need for a new
AIDS drug could not be more urgent.

U researcher Lana Barkawi has found some of
the strongest anti-HIV activity in propolis from southeast and
northern Minnesota and from China.

"About 36 million people are infected with HIV (the AIDS virus),
and 20 million have died of AIDS," he says. "Seventy-five percent
of the deaths have occurred in sub-Saharan Africa, but the epidemic
is rapidly shifting to India and Southeast Asia. Every day there
are 16,000 new infections." About a year ago, HIV passed
tuberculosis as the world's number one infectious disease. TB
remains the top opportunistic infection in HIV patients, however,
and it will wreak havoc in places like India, where sanitation and
access to high-quality health care is often poor. In many
countries, the cost of current AIDS drug therapies is prohibitive.
The three-drug "cocktail" that revolutionized AIDS treatment in the
developed world costs $10,000 a year in the United States, says
Peterson. In India, where generic formulations of the drugs are
available, it's $180 a year, but for a country whose average income
is $400 a year, that's still out of reach. At the U, the race is on
to document the specific anti-HIV functions of propolis, determine
which of its components are active, and find the geographical areas
where the most effective propolis is made, all in hopes of
discovering an effective but cheaper drug. Peterson and his
colleagues have examined the ability of propolis to stymie HIV
infections. HIV destroys the immune system by infecting white blood
cells called CD4 lymphocytes, the very cells that normally would
destroy a virus. HIV also attacks brain cells called microglia,
which help fight off infections in the nervous system. The
researchers grew the cells in culture with varying amounts of
propolis and added HIV. They found that the more propolis, the less
HIV grew inside the cells. Evidence suggested that propolis was
preventing the virus from entering the cells. Propolis also seemed
to work synergistically with the AIDS drug AZT. The U's Center for
Drug Design--headed by Robert Vince, the principal developer of the
AIDS drug Ziagen--is also involved in the effort. For example,
senior associate director Ramaiah Muthyala has found that propolis
inhibits enzymes that help HIV get established in the genomes of
host cells. It also inhibits the enzymes that help the virus
replicate. Conducting the tests was center member Jay Brownell, who
noted that propolis inhibits these enzymes much better than some
clinically used drugs, such as amprenavir and indinavir. Muthyala's
major effort centers on identifying the chemical structure of the
active component in propolis--once it's isolated--and developing a
means of synthesizing that active molecule in the laboratory. These
results are encouraging, but plenty remains to be done. Recognizing
the variability in trees and bees, Lana Barkawi, working in
entomology professor Jerry Cohen's lab, is testing propolis from
around the world. She has found some of the strongest anti-HIV
activity in propolis from southeast and northern Minnesota and from
China. Cohen and Barkawi are also trying to identify the
substance(s) in propolis responsible for its anti-HIV properties.
"If you want to get this approved by the FDA, you will have to
standardize it," says Peterson. "We believe it's critically
important to find the active ingredients in propolis." The propolis
project is an example of interdisciplinary research fostered by the
U's Center for Plants and Human Health. Center director Gary
Gardner is also an active member of the propolis team. The work is
funded by a $32,000 grant-in-aid from the Graduate School.